Method of forming a hydrofoil



'" Sept. 16, 1969 H. mm 3, 6 I

METHOD OF FORMING A HYDROFOIL Filed Jan. 5, 1964 Ha/ F/ad 60 56 76' 7 wINVENTOR.

@ H-ZMUT K0636 United States Patent 3,466,725 METHOD OF FORMING AHYDROFO-IL Helmut Kock, Woodlyn, Pa., assignor to Wilson Shipyard Inc.,a corporation of Delaware Filed Jan. 3, 1964, Ser. No."335,574 Int. Cl.B21k 3/04; B23p /02 U.S. Cl. 29-156.8 9 Claims ABSTRACT OF THEDISCLOSURE This invention relates to hydrofoils and more particularlyrelates to a method of forming a hydrofoil and the article formedthereby.

It is often required that a hydrofoil be constructed of severaldifferent parts, each having a number of different profiles along itslength, that is, that the width of the part and its thickness vary indifferent areas of the foil. Such hydrofoil parts are generally made ofaluminum, the aluminum being extruded to form a suitable shaped articlehaving a width and thickness equal to the maximum dimensions required,and then machined along its length to the desired contour and shape.Such machining, of course, requires a considerable amount of work,entails the use of very complex and costly machinery, and results in thewasting of a substantial amount of material. It has also been proposedto extrude the entire tapered foil or a part thereof, and while this ispossible, the extruding apparatus is very complex and expensive.Moreover, many different types of hydrofoil structures are required, andthe cost of providing the special dies and equipment for extruding allof them is prohibitive.

According to the present invention, it has now been found that thevarious parts of a hydrofoil structure may be constructed using a smallnumber of easily extrudable articles and a plurality of differentlyshaped cooperating plates. Once an article of suitable shape has beenextruded, it is split along its length, and a plate of suitableconfiguration is disposed between the two sections of the article. Thesections are then welded to the plate with the result that a completehydrofoil part is formed without the use of any complex or specialequipment or the wasting of a significant amount of material.

It is therefore an object of the present invention to provide a methodof forming a hydrofoil.

It is also an object of the present invention to provide a method offorming a hydrofoil or a hydrofoil part having different profiles alongits length.

It is another object of the present invention to provide a method offorming a hydrofoil or hydrofoil part by splitting an extruded articleand disposing a suitably shaped plate between the split sections.

It is a further object of the present invention to provide a new andimproved hydrofoil construction.

These and other objects and advantages of the present invention willbecome more apparent upon reference to the accompanying description anddrawings in which:

FIGURE 1 is a perspective view of a first form of elongated extrudedarticle;

FIGURE 2 is a sectional view of the article of FIGURE 1 after it hasbeen split lengthwise and a suitably shaped plate disposed between thetwo resulting sections;

3,466,725 Patented Sept. 16, 1969 FIGURE 3 is a sectional view of ahydrofoil part formed by welding together the three pieces of FIG- URE2;

FIGURE 4 is a perspective view of a second form of elongated extrudedarticle;

FIGURE 5 is a sectional view of the article of FIGURE 4 after it hasbeen split in two sections and a suitably shaped plate disposed betweenthe two resulting sections;

FIGURE 6 is a sectional view of a hydrofoil part formed by weldingtogether the three pieces shown in FIGURE 5;

FIGURE 7 is a sectional view of a structure formed by inserting a platebetween the two split sections of the article of FIGURE 4, the platehaving a greater thickness than the maximum thickness of the article;

FIGURE 8 is a cross sectional view of a hydrofoil formed by machiningdown the central plate of FIGURE 7 to obtain a smooth contour;

FIGURE 9 is a top plan view of a hydrofoil formed according to theteachings of the present invention;

FIGURE 10 is a sectional view taken along lines 1010 of FIGURE 9; and

FIGURE 11 is a perspective view of a section of an extruded article suchas shown in FIGURE 1 after it has been adapted for use in a hydrofoilsuch as that shown in FIGURE 9.

Referring now to FIGURES 1 through 3, there is shown three stages in afirst method of making a hydrofoil according to the present invention.In FIGURE 1 there is shown an elongated extruded article 10, preferablyof aluminum. As shown, this article is, in cross section, a circularsector defined by a bottom planar surface or chord 12, a top curvedsurface or camber 14 and leading and trailing edges 16 and 18. In thearticle shown, the greatest thickness is located at the midpoint of theplanar surface of chord 12. It should be obvious, however, that thisarea of greatest thickness can be located either forward or behind thismidpoint.

In order to form a hydrofoil having a longer chord than the extrudedarticle 10 (which could itself be used as a hydrofoil), the article 10is split lengthwise along the plane of greatest thickness. Preferably,the splitting plane is perpendicular to the chord or planar surface 12joining the leading and trailing edges 16 and 18. After the article 10has been split into two sections 20 and 22, a suitable solid plate 24 isdisposed between them. This plate 24 may be rectangular in crosssection, the vertical sides 26 and 28 thereof being parallel to thesplit surfaces 30 and 32 of the sections 20 and 22, the plate 24 beingof the same vertical dimension of the split surfaces 30 and 32.

Before the sections 20 and 22 and plate 24 are assembled, weldinggrooves 34 are formed in these members. The parts are then weldedtogether, the groove being filled with welded metal. Grinding of thewelds and fairing out of the surface completes the procedure of thisconstruction. By providing the plate 24 with a taper along its length,the hydrofoil may be provided with a similar taper, the chordsuccessively decreasing along its length. Such a hydrofoil is indicatedin phantom in FIG- URE 3.

Referring now to FIGURE 4, there is shown a second form of extrudedarticle 40. This article has lower and upper curved surfaces or cambers42 and 44 joining the leading edge 46 to the trailing edge 48. As can beseen from this figure, the thickest portion of this article occurs in aplane offset from the center of the article towards the front thereof.The process of forming a hydrofoil having a wider profile than thearticle 40 is similar to that described previously. The article 40 issplit lengthwise along the plane of greatest thickness to form twosections 50 and 52 and a suitable plate 54 is disposed between them.Suitable welding grooves 56 are then formed and the various parts weldedtogether. As was the case with the plate 24, the plate 54 may be taperedto provide the hydrofoil with a changing profile over its length.

Referring now to FIGURE 7, there is shown a structure formed in a mannersimilar to the hydrofoil of FIG- URE 6 with the exception that the plate58 inserted between the sections 50 and 52 is thicker than the greatestthickness of these sections. By providing such a thicker plate, ahydrofoil having a continuous curvature can be formed as is shown inFIGURE 8. In this figure, the plate 58 and welding material 60 in thewelding grooves 56 has been machined and faired to obtain the continuouscurved surface.

Referring now to FIGURE 9, there is shown another form of hydrofoil partconstructed according to the present invention. In this embodiment ofthe invention, an extruded article similar to that shown at is splitinto two sections 62 and 64 as previously described. However, in thisembodiment, the two sections are not positioned in parallel relation butare rather disposed at an angle to each other. For this purpose, aportion of each section at the intersecting end is removed along a planerunning at an angle to the original cut. This leaves a split surface 66angling away from the center of the section to the edge thereof. As aresult of this cut, the maximum thickness of the end surface 68 of thesection will be less than the thickness of the longitudinally cutsurface 70. The hydrofoil part is thus provided with both horizontal andvertical taper. The ends of the sections 62 and 64 are preferablysquared off, the original section being shown in phantom in FIGURE 11.

After the sections 62 and 64 have been properly cut, a suitabletriangular plate is disposed between them. This plate may, if desired,be a solid plate such as that previously described. In this event, it ispreferred that the plate be made slightly thicker than the extrudedarticle and then machined to proper size in the manner described inconnection with FIGURES 7 and 8. Alternatively, a pair of thinner plates72 and 74 and a reinforcing rib 76 may be used. As shown in FIGURE 10,the upper plate 72 continues the curvature of the sections 64 and 62while the bottom plate 74 is fiat. As in the other embodiments, thecomponents are welded together to form the finished hydrofoil. Thelatter construction permits a considerable savings of material andWeight over a solid central plate. It is obvious, of course, that thismethod of construction could also be used in place of the solid plates24, 54 and 58 used in the previous embodiments, and that an articlehaving both upper and lower curved surfaces could be used in the methoddescribed in connection with FIG- URES 9 to 11.

From the foregoing description, it may be seen that the presentinvention provides improved methods of constructing hydrofoils orhydrofoil parts. By use of the present invention, a large number ofdifferently shaped hydrofoil parts can be constructed from a minimumnumber of easily extrudable articles used in cooperation with platesthat can be easily connected to the sections of the extruded articlesafter the extruded articles have been split in a desired manner. Thepresent invention thereby eliminates the need for complex and costlyequipment and keeps the amount of material wasted to a minimum.

The invention may be embodied in other specific forms not departing fromthe spirit or central characteristics thereof. The present embodimentsare therefore to be considered in all respects as illustrative and notrestrictive, the scope of the invention being indicated by the appendedclaims rather than by the foregoing description, and all changes whichcome within the meaning and range of equivalency of the claims aretherefore intended to be embraced therein.

4 I claim: 1. A method of forming a hydrofoil comprising the steps of:

forming a body having a leading edge, a trailing edge,

and at least one curved surface joining said edges;

splitting said body lengthwise between said edges to produce twosections;

disposing a plate between said sections; and

fixedly connecting the split surfaces of said sections to said platealong at least a portion of their length.

2. A method of forming a hydrofoil comprising the steps of:

extruding an elongated, shaped article having a leading edge, a trailingedge and at least one curved surface joining said edges;

splitting said body along its entire length to produce two sections;

disposing a plate between said sections; and

adhering the split surfaces of said sections to said plate along atleast a portion of their length.

3. A method of forming a hydrofoil comprising the steps of extruding anelongated, shaped article having a leading edge, a trailing edge and, atleast one curved surface joining said edges; splitting said articlealong its entire length in a plane intersecting the plane joining saidleading edge with said trailing edge to produce two sections;

disposing a plate having sides substantially parallel to the splitsurfaces of said sections between said sections; and

adhering the split surfaces of said sections to said sides of said platealong at least a portion of their length.

4. The method of claim 3 wherein said article is split along its planeof greatest thickness.

5. The method of claim 4 wherein said plate has a vertical dimensionsubstantially equal to those of said split surfaces.

6. A method of forming a hydrofoil comprising the steps of:

extruding an elongated, shaped article having a leading edge, a trailingedge and at least one curved surface joining said edges; splitting saidarticle along its entire length in a plane perpendicular to the planejoining said leading edge with said trailing edge to produce twosections;

disposing a plate, generally rectangular in cross section,

between said sections;

forming welding grooves in said plate and said sections;

and

uniting the split surfaces of said sections to said plate along at leasta portion of their length.

7. The method of claim 6 wherein said plate is machined to match thecurvature of said curved surface.

8. A method of forming a hydrofoil comprising the steps of:

extruding an elongated, shaped article having a leading edge, a trailingedge and at least one curved surface joining said edges; splitting saidarticle along its entire length in a plane perpendicular to the planejoining said leading edge with said trialing edge to produce twosections;

disposing a plate, generally rectangular in cross section,

between said sections; and

welding the split surfaces of said sections to said plate along theirentire length.

9. A method of forming a hydrofoil comprising the steps of:

extruding an elongated, shaped article having a leading edge, a trailingedge and at least one curved surface joining said edges;

splitting said article along its entire length in a plane substantiallyperpendicular to the plane joining said leading edge with said trailingedge to produce two sections;

removing an equal portion of each of said sections from one end of thesplit surface thereof;

disposing a generally tapered plate between said sections; and

adhering said sections together in the area where the portions wereremoved and adhering the remainder of the split surfaces of saidsections to said plate.

References Cited 6 Simmonds 244-124 X Soderberg 29156.8 Brequet 224124Ewald et a1 29156.8 X Erwin 244124 X Shultz 29156.8

JOHN F. CAMPBELL, Primary Examiner D. C. REILEY, Assistant Examiner U.S.C1. X.Rv

